Dendrochronology and carbon 14 dating
As one of the principal objectives of this analysis has been to understand more fully the nature and causes of the variability of radiocarbon dates, the data were examined carefully for signs of non-random errors. Much of the data collected in the early stage of investigation was of an extremely difficult quality, with a very low average ring width (many specimens had more than 100 rings per radial inch), a high mean sensitivity, and many locally absent and missing rings.
A 7104 Year Annual Tree Ring Chronology for Bristlecone Pine, Pinus Aristata, from the White Mountains, California – C. Ferguson – Tree-Ring Bulletin, Volume 29 (1969) https://arizona.openrepository.com/arizona/bitstream/10150/259957/1/trb-29-03-04-003-029The discussions between the two disciplines must have had a few interesting moments because Radiocarbon Dating [much to their surprise] conceded that “there is significant evidence of systematic differences between the laboratories”. – Radiocarbon, 24, 1982 https://arizona.edu/index.php/radiocarbon/article/download/748/753? origin=publication_detail The composite “workshop data set” is plotted against the 6th order polynominal regressed on the logarithmically scaled data.
Variation in these rings is due to variation in environmental conditions when they were formed.
Thus, studying this variation leads to improved understanding of past environmental conditions and is the basis for many research applications of dendrochronology.
The accuracy of the machines is not in question (especially modern ones, which are astoundingly accurate when properly zeroed in). But, any source of old carbon in the ancient environment can affect the amount of C-14 in a sample.
Examples: For all of these, and more, reasons, calibration is needed in C-14 dating.
Thus, reports generally specify the ‘raw’ numbers and the ‘fudged’ numbers.
This does not mean that recalibration is bad, indeed it is necessary, but it should make one more soberly assess any reported dates as being tentative.
This work includes measurements on wood as old as 8000 years. Radiocarbon Dating wanted to “understand more fully the nature and causes of the variability of radiocarbon dates” whilst Dendrochronology needed to ensure their Bristlecone Pine chronology [aka narrative] based upon a “new dendrochronological species, in a new area, and (increasingly) in a new time period” was not derailed by Radiocarbon Dating. – Radiocarbon, 24, 1982 https://arizona.edu/index.php/radiocarbon/article/download/748/753? origin=publication_detail This study brought out what was very early realized: that in working with a new dendrochronological species, in a new area, and (increasingly) in a new time period, we would be much more secure in chronology building to work with material of a proven, but safe quality.Much to our surprise and despite previous findings to the contrary (Damon, Lerman, and Long, 1978; Clark, 1975; Damon, 1970), there is significant evidence of systematic differences between the laboratories represented. Calendric age minus conventional radiocarbon age is the ordinate; the calendric age is the abscissa. – Radiocarbon, 24, 1982 https://arizona.edu/index.php/radiocarbon/article/download/748/753? origin=publication_detail However, an analysis of the “workshop data set” reveals that Radiocarbon Dating of the Bristlecone Pine chronology is far from a perfect fit and that the rounded consensus calibration curve is derived from a very jagged, saw tooth dataset.) of the White Mountains of Eastern California, were dated in 1957 by counting tree rings at 4,723 years old.A tree ring pattern that matches is found close to where the carbon ‘dates’ are the same. It assumes that it is approximately correct to linearly extrapolate the carbon ‘clock’ backwards. The closer one gets back to the Flood the more inaccurate the linear extrapolation of the carbon ‘clock’ would become, perhaps radically so.